1. Field
One or more embodiments of the present invention relate to a photoacoustic probe and a photoacoustic diagnostic apparatus including the same for use in diagnosis from photoacoustic images.
2. Description of the Related Art
A photoacoustic imaging technology uses a photoacoustic effect to noninvasively image biological tissues. When a biological tissue is irradiated with a short electromagnetic laser pulse for photoacoustic imaging, some of the energy of the laser pulse is absorbed into the biological tissue and converted into heat, thereby causing thermo-elastic expansion. The thermo-elastic expansion leads to emission of wideband ultrasound waves, and the emitted ultrasound waves are detected by ultrasound transducers from different directions and reconstructed into images.
Since photoacoustic imaging is based on the conversion of electrical signals into ultrasound waves for detection, this method has advantages of combining properties of optical imaging with those of ultrasound imaging. Pure optical imaging has much higher resolution than ultrasound imaging, but permits only limited imaging up to a predetermined depth from a surface of a living tissue due to strong optical scattering of soft tissues. On the other hand, ultrasound imaging provides a sufficiently high spatial resolution so as to examine a fetus. Photoacoustic imaging overcomes the drawback of optical imaging such as low imaging depths with conversion into ultrasound waves due to a photoacoustic effect, thereby achieving both a high optical contrast ratio and a high spatial resolution.
Photoacoustic imaging techniques have already been developed significantly to conduct research on tumors, brains, hearts, and eyeballs of small animals. With a tendency toward combination of detection of excited light with ultrasound detection, a photoacoustic imaging system may easily be integrated with a conventional ultrasound imaging system after undergoing only a slight modification such as removal of an ultrasound transmission function and addition of a radio frequency (RF) data collection function). Due to its sharing of an acoustic detector, the integrated system may provide advantages of a traditional ultrasound imaging system such as portability and real-time imaging capability.